1. Field of the Invention
The present invention relates to the measurement of energy and power associated with electromagnetic radiation, in particular with radio-frequency, microwave and light radiation signals.
More specifically, the invention relates to a sensor and a bolometric device for measuring energy and power in radio-frequency, microwave and optical-type circuits.
2. Description of Related Art
Measurements of energy and power in radio-frequency and microwave circuits are at present carried out with devices of various types according to the field of use. Measurements of this type are in fact rather delicate and are based on the use of various types of sensors according to the power range to be measured. The powers in question in fact vary across a very wide range which extends through various orders of size, typically from -70 dBm to +30 dBm and beyond. In order to cover such a range, known instruments use various types of sensor for the detection of the radio-frequency energy, such as calorimetric or bolometric sensors, sensors with thermocouples and with diodes, according to the field of use. These sensors, as well as the associated devices, have serious limitations as far as applicability, precision, stability and other parameters are concerned. For example, diodes can be used in the low band of power, while thermocouples are preferably used in the high band, with the result of limiting the field of use of the instruments, or requiring complex solutions in order to change the range of the instruments and similar. Further disadvantages of known sensors, in particular of high-sensitivity models with diodes, are represented by high values of maladjustment at the various frequencies (high standing-wave ratios); calibration and compensation are necessary for each sensor in order to take account of the individual characteristics of the diodes; and there is limited capacity for withstanding power transients. As far as measurements of energy and power with regard to light radiation are concerned, these are carried out with instruments of various types, such as for example the volt-ampere meters HP 8152A, 8151A and similar, despite the interaction and the combined use, which are ever more frequent, of signals of the electrical type and signals of the optical type.